The present invention relates to a head adjusting device provided with, for example, a magnetic recording apparatus for recording and reproducing data to and from a magnetic disk. More particularly, the present invention is drawn to a head adjusting device arranged in such a manner that a positional relationship adjustment thereof to a desired position, for example, an initial tracking position or a final tracking position and so forth, can be easily executed.
In a magnetic data recording apparatus for recording and reproducing data to and from a magnetic disk such as a floppy disk and the like, the recording and reproducing operations are carried out by causing a magnetic head to come into contact with the recording surface of the magnetic disk arranged to be rotated.
The recording surface of this type of magnetic disk has a multiplicity of concentric magnetic recording tracks. The magnetic head comes into contact with any one of these tracks for effecting the recording and reproducing. It is then moved in the radial direction thereof for effecting recording and reproducing for the desired recording track.
FIG. 1 shows an example of a conventional head adjusting device for moving a carriage on which the above magnetic head is mounted, in a tracking direction, indicated by an arrow T', of the magnetic disc. In FIG. 1, 1' designates the magnetic head and 2' designates a carriage for supporting the magnetic head 1' thereon. The carriage 2' is slidably supported by two parallel guide bars 3', 4', respectively fixed to a chassis, not shown, of the magnetic data recording apparatus. The carriage is urged in a direction substantially parallel to the tracking direction of the disc and toward the center of the disc by a bias force applied by means of a spring 6'. A spindle motor 5', including a spindle 5a', is provided for rotating the magnetic disc. A step motor 11', fixed to a base, not shown, is provided on the chassis or the like, by means of a pair of screws 15', 15', passing through slots 11b', 11b', defined in both side flanges of the step motor 11'.
The above step motor 11' is provided with a pinion 9', which is brought into engagement with a driven gear 10' to enable a spiral cam 7', coaxially provided with the driven gear 10', to be rotated. The cam 7' comes into contact with a cam follower 8' provided on the carriage 2', and the carriage 2', as well as the magnetic head 1', supported by the carriage 2', are moved in the tracking direction by rotation of the cam 7'.
Positional adjustment of the magnetic head 1' is conventionally carried out such that a rotational shaft of the step motor 11', not shown, is locked so as not to be rotated by energization of the step motor 11'. The step motor 11' is then excited while the screws 15' are loosened. Thus, the main body of the step motor 11' is rotated along the slots 11b' about the rotational shaft of the step motor 11', and the spiral cam 7' is directly rotated, without a rotation of the rotational shaft of the step motor 11', through the driven gear 10', to cause the carriage to move in the tracking direction T'.
In the conventional device, however, a problem arises in that the adjustable range is limited by the speed reduction ratio between the pinion 9' and the driven gear 10', which is defined by the number of teeth of the pinion 9' and the driven gear 10'. In other words, since the cam 7' is only slightly rotated in accordance with the speed reduction ratio, the adjustable range is extremely limited. Further, another problem also arises in that a sufficient dead space is needed to enable a terminal plate 11a, through which electrical power for driving the step motor 11' is supplied, projecting from the step motor 11' to be rotated during the above position adjusting operation.